With rapid development of communications technologies and popularization of intelligent user terminals, a user terminal can be connected to either a wireless cellular network or a wireless local area network (WLAN).
The user terminal may select, according to a specified policy, a specific communications standard to perform data communication separately. In a separate operation process by using a WLAN standard (for example, a WiFi technology), a WLAN communication link fails in communication because a shared radio channel is busy, or a like reason, causing an unstable transmission speed.
However, switching from a WLAN communications standard to a wireless cellular communications standard is confronted with another problem:
If a user terminal and an Internet service server are considered as two ends of a user service flow, the service flow uses entirely different internet protocol (IP) addresses and routing paths when the service flow is switched between different communications standards. The changes of the IP addresses and routing paths result in unavoidable interruption of the service flow, such as video freezing, web page reopening, and voice call interruption.